Improvement in fire-proof metallic roofing



UNITED STATES PATENT OFFICE.

ALFRED C. DE LA MARTELLIERE, OF PARIS, FRANCE.

IMPROVEMENT IN FIRE-PROOF METALLIC ROOFING.

Specification forming part of Letters Patent No. 190,834, dated May 15,1877 application filed April 21, 1877.

To all whom a may concern.-

Be it known that I, ALFRED OAMILLE DE LA MABTELLIERE, of Paris, France,have invented a new and useful Improvement in the Art of MakingFire-Proof Metallic Roofing; and 1 do hereby declare that the followingis a full, clear, and exact description thereof.

My invention consists in producing fireproof roofing by first coveringthe surface of iron plates with a coating of lead and tin,

a short time, for the purpose of removing all oxidation from theirsurfaces, which leaves them in a state to absorb the coating of lead andtin, the first step in the deposition, and to receive the final depositof zinc, hereinafter described.

Plates thus prepared are immersed in a bath of melted lead, having asmall proportion of tin, to the surface of which plates will adhere acovering, inseparably connected and absorbed in their surfaces, as itwere, which covering more readily receives the subsequent deposit ofzinc, which commingles with the lead and tin, and presents a surface,fireproof, consisting of lead, tin, and zinc, being part and parcel ofthe iron plates as a base.

These plates are next immersed in a solution of chloride of zinc andhydrochlorate of ammonia, being immersed and withdrawn several times,remaining in this solution but a few moments at each immersion.

The next stage in this process is to place these plates into a solutionof zinc, and deposit upon their surfaces the finally-required coating.

In this solution of zinc a portion of the lead and tin, which the ironaccepts while passing through the first stage of this process, runs offand settles at the bottom of the solution, and finds itself replaced bya coating of zinc, forming a homogeneous surface therewith.

The plates, thus doubly galvanized, are taken from the zinc-bath andwashed in Water to free them from what may adhere of the solution, whichcompletes the process of what I term double galvanization.

The plates, thus prepared, are composed mostly of iron, the iron beingfirst covered with a light coating of lead and tin, and subsequentlycovered with a deposition of zinc.

This method of galvanizing produces several advantages, the mostimportant of which is that the deposit of zinc is much more adhesivethan if deposited simply upon the iron without previous preparation, thecovering of lead and tin serving as a sort of combination between theiron and zinc.

Iron plates thus prepared produce a combibination of about .98 of leadand .02 of tin, of which only a small quantity, a thin layer, remains,and the final deposit of zinc thereon for roofing should be aboutone-fifth or onesixth of the total thickness.

The incombustibility of these plates results from the peculiarcombination of the different metals of which they are composed. Thezinc, which is the only metal really combustible, is present only insuch a state that it cannot burn.

Having thus fully described my invention, what I claim therein as new,and desire to secure by Letters Patent, is-

The process of rendering metallic plates for roofing fire-proof, byfirst covering their surfaces with a coating of lead and tin, immersingthese plates so covered in a bath of chloride of zinc and hydrochlorateof ammonia, and subsequently depositing thereon a covering of zinc,substantially as herein set forth.

A. 0. DE LA MARTELLIERE.

Witnesses:

E. LE COUBNELLE, O. V. MoT.

